3  * Fence mechanism for dma-buf to allow for asynchronous dma access
31  * @refcount: refcount for this fence
32  * @ops: dma_fence_ops associated with this fence
33  * @rcu: used for releasing fence with kfree_rcu
36  * @context: execution context this fence belongs to, returned by
38  * @seqno: the sequence number of this fence inside the execution context,
39  * can be compared to decide which fence would be signaled later.
41  * @timestamp: Timestamp when the fence was signaled.
43  * dma_fence_signal, indicates that the fence has completed with an error.
49  * DMA_FENCE_FLAG_SIGNALED_BIT - fence is already signaled
50  * DMA_FENCE_FLAG_TIMESTAMP_BIT - timestamp recorded for fence signaling
53  * implementer of the fence for its own purposes. Can be used in different
54  * ways by different fence implementers, so do not rely on this.
70 	 * release the fence it is unused. No one should be adding to the
79 	 * and to read either you *must* hold a reference to the fence,
105 typedef void (*dma_fence_func_t)(struct dma_fence *fence,
110  * @node: used by dma_fence_add_callback() to append this struct to fence::cb_list
122  * struct dma_fence_ops - operations implemented for fence
139 	 * for each fence, or build a cache of some sort.
143 	const char * (*get_driver_name)(struct dma_fence *fence);
148 	 * Return the name of the context this fence belongs to. This is a
150 	 * having it to store permanently for each fence, or build a cache of
155 	const char * (*get_timeline_name)(struct dma_fence *fence);
160 	 * Enable software signaling of fence.
162 	 * For fence implementations that have the capability for hw->hw
167 	 * dma_fence_wait() or dma_fence_add_callback() path to let the fence
174 	 * A return value of false indicates the fence already passed,
183 	 * dma_fence_signal() might result in the final fence reference being
186 	 * released when the fence is signalled (through e.g. the interrupt
192 	bool (*enable_signaling)(struct dma_fence *fence);
197 	 * Peek whether the fence is signaled, as a fastpath optimization for
199 	 * callback does not need to make any guarantees beyond that a fence
201 	 * callback. This callback may return false even if the fence has
209 	bool (*signaled)(struct dma_fence *fence);
222 	 * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
224 	 * which should be treated as if the fence is signaled. For example a hardware
227 	signed long (*wait)(struct dma_fence *fence,
233 	 * Called on destruction of fence to release additional resources.
238 	void (*release)(struct dma_fence *fence);
243 	 * Callback to fill in free-form debug info specific to this fence, like
248 	void (*fence_value_str)(struct dma_fence *fence, char *str, int size);
254 	 * sequence number. Note that the specific fence passed to this function
258 	void (*timeline_value_str)(struct dma_fence *fence,
264 	 * Callback to allow a fence waiter to inform the fence signaler of
266 	 * would prefer the fence to be signaled by.  This is intended to
267 	 * give feedback to the fence signaler to aid in power management
279 	void (*set_deadline)(struct dma_fence *fence, ktime_t deadline);
282 void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
286 void dma_fence_free(struct dma_fence *fence);
287 void dma_fence_describe(struct dma_fence *fence, struct seq_file *seq);
290  * dma_fence_put - decreases refcount of the fence
291  * @fence: fence to reduce refcount of
293 static inline void dma_fence_put(struct dma_fence *fence)  in dma_fence_put()  argument
295 	if (fence)  in dma_fence_put()
296 		kref_put(&fence->refcount, dma_fence_release);  in dma_fence_put()
300  * dma_fence_get - increases refcount of the fence
301  * @fence: fence to increase refcount of
303  * Returns the same fence, with refcount increased by 1.
305 static inline struct dma_fence *dma_fence_get(struct dma_fence *fence)  in dma_fence_get()  argument
307 	if (fence)  in dma_fence_get()
308 		kref_get(&fence->refcount);  in dma_fence_get()
309 	return fence;  in dma_fence_get()
313  * dma_fence_get_rcu - get a fence from a dma_resv_list with
315  * @fence: fence to increase refcount of
317  * Function returns NULL if no refcount could be obtained, or the fence.
319 static inline struct dma_fence *dma_fence_get_rcu(struct dma_fence *fence)  in dma_fence_get_rcu()  argument
321 	if (kref_get_unless_zero(&fence->refcount))  in dma_fence_get_rcu()
322 		return fence;  in dma_fence_get_rcu()
328  * dma_fence_get_rcu_safe  - acquire a reference to an RCU tracked fence
329  * @fencep: pointer to fence to increase refcount of
331  * Function returns NULL if no refcount could be obtained, or the fence.
332  * This function handles acquiring a reference to a fence that may be
334  * so long as the caller is using RCU on the pointer to the fence.
339  * fence is acquired (as shown here).
347 		struct dma_fence *fence;  in dma_fence_get_rcu_safe()  local
349 		fence = rcu_dereference(*fencep);  in dma_fence_get_rcu_safe()
350 		if (!fence)  in dma_fence_get_rcu_safe()
353 		if (!dma_fence_get_rcu(fence))  in dma_fence_get_rcu_safe()
359 		 * to the __rcu protected fence pointer so that if that  in dma_fence_get_rcu_safe()
360 		 * pointer still matches the current fence, we know we  in dma_fence_get_rcu_safe()
365 		 * fence remains valid for the RCU grace period, but it  in dma_fence_get_rcu_safe()
368 		 * the right fence, as below.  in dma_fence_get_rcu_safe()
370 		if (fence == rcu_access_pointer(*fencep))  in dma_fence_get_rcu_safe()
371 			return rcu_pointer_handoff(fence);  in dma_fence_get_rcu_safe()
373 		dma_fence_put(fence);  in dma_fence_get_rcu_safe()
390 int dma_fence_signal(struct dma_fence *fence);
391 int dma_fence_signal_locked(struct dma_fence *fence);
392 int dma_fence_signal_timestamp(struct dma_fence *fence, ktime_t timestamp);
393 int dma_fence_signal_timestamp_locked(struct dma_fence *fence,
395 signed long dma_fence_default_wait(struct dma_fence *fence,
397 int dma_fence_add_callback(struct dma_fence *fence,
400 bool dma_fence_remove_callback(struct dma_fence *fence,
402 void dma_fence_enable_sw_signaling(struct dma_fence *fence);
405  * dma_fence_is_signaled_locked - Return an indication if the fence
407  * @fence: the fence to check
409  * Returns true if the fence was already signaled, false if not. Since this
419 dma_fence_is_signaled_locked(struct dma_fence *fence)  in dma_fence_is_signaled_locked()  argument
421 	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))  in dma_fence_is_signaled_locked()
424 	if (fence->ops->signaled && fence->ops->signaled(fence)) {  in dma_fence_is_signaled_locked()
425 		dma_fence_signal_locked(fence);  in dma_fence_is_signaled_locked()
433  * dma_fence_is_signaled - Return an indication if the fence is signaled yet.
434  * @fence: the fence to check
436  * Returns true if the fence was already signaled, false if not. Since this
449 dma_fence_is_signaled(struct dma_fence *fence)  in dma_fence_is_signaled()  argument
451 	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))  in dma_fence_is_signaled()
454 	if (fence->ops->signaled && fence->ops->signaled(fence)) {  in dma_fence_is_signaled()
455 		dma_fence_signal(fence);  in dma_fence_is_signaled()
464  * @f1: the first fence's seqno
465  * @f2: the second fence's seqno from the same context
486  * @f1: the first fence from the same context
487  * @f2: the second fence from the same context
502  * dma_fence_later - return the chronologically later fence
503  * @f1:	the first fence from the same context
504  * @f2:	the second fence from the same context
506  * Returns NULL if both fences are signaled, otherwise the fence that would be
529  * @fence: the dma_fence to query
532  * the fence (to indicate whether the fence was completed due to an error
534  * if the fence has been signaled, dma_fence_get_status_locked() first checks
537  * Returns 0 if the fence has not yet been signaled, 1 if the fence has
539  * if the fence has been completed in err.
541 static inline int dma_fence_get_status_locked(struct dma_fence *fence)  in dma_fence_get_status_locked()  argument
543 	if (dma_fence_is_signaled_locked(fence))  in dma_fence_get_status_locked()
544 		return fence->error ?: 1;  in dma_fence_get_status_locked()
549 int dma_fence_get_status(struct dma_fence *fence);
552  * dma_fence_set_error - flag an error condition on the fence
553  * @fence: the dma_fence
557  * the fence, to indicate that the fence was completed due to an error
562 static inline void dma_fence_set_error(struct dma_fence *fence,  in dma_fence_set_error()  argument
565 	WARN_ON(test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags));  in dma_fence_set_error()
568 	fence->error = error;  in dma_fence_set_error()
572  * dma_fence_timestamp - helper to get the completion timestamp of a fence
573  * @fence: fence to get the timestamp from.
575  * After a fence is signaled the timestamp is updated with the signaling time,
579 static inline ktime_t dma_fence_timestamp(struct dma_fence *fence)  in dma_fence_timestamp()  argument
581 	if (WARN_ON(!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)))  in dma_fence_timestamp()
584 	while (!test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags))  in dma_fence_timestamp()
587 	return fence->timestamp;  in dma_fence_timestamp()
598  * dma_fence_wait - sleep until the fence gets signaled
599  * @fence: the fence to wait on
603  * or 0 if the fence was signaled. Other error values may be
606  * Performs a synchronous wait on this fence. It is assumed the caller
607  * directly or indirectly holds a reference to the fence, otherwise the
608  * fence might be freed before return, resulting in undefined behavior.
612 static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)  in dma_fence_wait()  argument
620 	ret = dma_fence_wait_timeout(fence, intr, MAX_SCHEDULE_TIMEOUT);  in dma_fence_wait()
625 void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);
635  * dma_fence_is_array - check if a fence is from the array subclass
636  * @fence: the fence to test
640 static inline bool dma_fence_is_array(struct dma_fence *fence)  in dma_fence_is_array()  argument
642 	return fence->ops == &dma_fence_array_ops;  in dma_fence_is_array()
646  * dma_fence_is_chain - check if a fence is from the chain subclass
647  * @fence: the fence to test
651 static inline bool dma_fence_is_chain(struct dma_fence *fence)  in dma_fence_is_chain()  argument
653 	return fence->ops == &dma_fence_chain_ops;  in dma_fence_is_chain()
657  * dma_fence_is_container - check if a fence is a container for other fences
658  * @fence: the fence to test
660  * Return true if this fence is a container for other fences, false otherwise.
661  * This is important since we can't build up large fence structure or otherwise
664 static inline bool dma_fence_is_container(struct dma_fence *fence)  in dma_fence_is_container()  argument
666 	return dma_fence_is_array(fence) || dma_fence_is_chain(fence);  in dma_fence_is_container()